Hi Tom,

I'm hoping you can help give us guidance to solve an intermittent issue we are experiencing with our machine. The problem started about a week ago, we operated the machine for about 2-3 weeks prior with no similar issues before this problem began.

Generally after first turning on the machine it will function normally for a few minutes and then suddenly all of the axis will start moving with violent jerks and vibrations. The issue occurs on all axis simultaneously for a varying period of time after which they start to behave normally again. An episode can last from a few seconds to a few minutes, once it passes the machine will operate normally for a random period of time (up to 10-15 minutes) and then another episode will occur. In a few rare cases the issue occurred immediately upon turning on the machine, but generally it runs for a minute or two before we see it.

There is no discernible pattern we have found that causes an episode. It can occur while jogging, cutting, executing move commands, moving in any direction along the axis,and at any location on the table.

Our setup:
2 SnapAmp with Kanalog card
4 Axis each with their own power supply
DC servo motors dirrentially encoded
Encoder cables are shielded and grounded
Dedicated 5V power supply for the kflop.

Our init.c file: http://www.filedropper.com/init (click Download This File)


We have nothing flashed to the kflop at the moment. We have tried running the kflop with 4.32, 4.33d, and 4.33j, this has no effect on the issue.


Since the issue began we have tried to eliminate the possibility of noise as the culprit by ensuring there are no ground loops, we have isolated the kflop from ground by running it off a laptop and by powering the kflop's 5V supply with UPS battery. There is still some noise on the 5V supply during normal operation of the machine that can't be avoided. Since the machine worked normally before we made efforts to reduce the noise I'm doubtful that our issue is noise related, but just in case this is what the 5VDC looks like while the axis are moving:

5VDC_zpsa57b6350.jpg Photo by David_Piccolo | Photobucket

I've managed to gather step response data during an episode,as you will see there are blips in the encoder position that cause this violent reaction.

Step Response Data: http://www.filedropper.com/x1_2 (click Download This File)

We have tested our encoders separately by individually powering them and pushing the axis, the pulses are consistent, they do not show any variation or malformation. Since the issue occurs on all axis it seems unlikely that this is an encoder issue.

At the moment we are at a loss as to the root cause of this problem, the common denominators between all the axis are few. I would greatly appreciate any insight you can provide to point us in the right direction.

Sincerely,
David.

Ps. This is my first time using file dropper, it seems to work but if there are any issues let me know.